Connect to Azure Blob Storage

This page describes how consuming apps connect to an Azure Blob Storage resource that’s already modeled in your AppHost. For the AppHost API surface — adding a storage account, blob resources, blob containers, Azurite emulator, role-based access, and more — see Azure Blob Storage Hosting integration.

When you reference an Azure Blob Storage resource from your AppHost, Aspire injects the connection information into the consuming app as environment variables. Your app can either read those environment variables directly — the pattern works the same from any language — or, in C#, use the Aspire Azure Blob Storage client integration for automatic dependency injection, health checks, and telemetry.

Connection properties

Aspire exposes each property as an environment variable named [RESOURCE]_[PROPERTY]. For instance, the Uri property of a resource called blobs becomes BLOBS_URI.

Blob storage resource

The blob storage resource (AddBlobs / addBlobs) exposes the following connection properties:

Property Name	Description
Uri	The blob service endpoint, with the format https://{account}.blob.core.windows.net/
ConnectionString	Emulator only. The full connection string for the Azurite emulator

Example:

Uri: https://mystorageaccount.blob.core.windows.net/

Blob container resource

The blob container resource (AddBlobContainer / addBlobContainer) inherits all properties from its parent blob storage resource and adds:

Property Name	Description
BlobContainerName	The name of the blob container in Azure Storage

Example:

Uri: https://mystorageaccount.blob.core.windows.net/
BlobContainerName: upload-data

Connect from your app

Pick the language your consuming app is written in. Each example assumes your AppHost adds an Azure Storage resource, adds a blob service resource named blobs, and references it from the consuming app.

C#

For C# apps, the recommended approach is the Aspire Azure Blob Storage client integration. It registers a BlobServiceClient through dependency injection and adds health checks and telemetry automatically. If you’d rather read environment variables directly, see the Read environment variables section at the end of this tab.

Install the client integration

Install the 📦 Aspire.Azure.Storage.Blobs NuGet package in the client-consuming project:

.NET CLI

.NET CLI — Add Aspire.Azure.Storage.Blobs package

dotnet add package Aspire.Azure.Storage.Blobs

Program.cs (C# file-based app)

Program.cs

#:package Aspire.Azure.Storage.Blobs@*

PackageReference (*.csproj)

XML — Add Aspire.Azure.Storage.Blobs package reference

<PackageReference Include="Aspire.Azure.Storage.Blobs" Version="*" />

Add the Blob Storage client

In Program.cs, call AddAzureBlobServiceClient on your IHostApplicationBuilder to register a BlobServiceClient:

C# — Program.cs

builder.AddAzureBlobServiceClient(connectionName: "blobs");

提示

The connectionName must match the blob resource name from the AppHost. For more information, see Add blob resource.

Resolve the client through dependency injection:

C# — ExampleService.cs

public class ExampleService(BlobServiceClient client)
{
    // Use client...
}

Add keyed Blob Storage clients

To register multiple BlobServiceClient instances with different connection names, use AddKeyedAzureBlobServiceClient:

C# — Program.cs

builder.AddKeyedAzureBlobServiceClient(name: "images");
builder.AddKeyedAzureBlobServiceClient(name: "documents");

Then resolve each instance by key:

C# — ExampleService.cs

public class ExampleService(
    [FromKeyedServices("images")] BlobServiceClient imagesClient,
    [FromKeyedServices("documents")] BlobServiceClient documentsClient)
{
    // Use clients...
}

For more information, see .NET dependency injection: Keyed services.

Configuration

The Aspire Azure Blob Storage client integration offers multiple ways to provide configuration.

Connection strings. When using a connection string from the ConnectionStrings configuration section, pass the connection name to AddAzureBlobServiceClient:

C# — Program.cs

builder.AddAzureBlobServiceClient("blobs");

Two connection formats are supported:

Service URI (recommended for production with managed identity or default credentials):

JSON — appsettings.json

{
  "ConnectionStrings": {
    "blobs": "https://{account_name}.blob.core.windows.net/"
  }
}

Connection string (useful for local development with Azurite):

JSON — appsettings.json

{
  "ConnectionStrings": {
    "blobs": "AccountName=devstoreaccount1;AccountKey=...;BlobEndpoint=http://localhost:10000/devstoreaccount1"
  }
}

Configuration providers. The client integration supports Microsoft.Extensions.Configuration. It loads AzureStorageBlobsSettings from appsettings.json using the Aspire:Azure:Storage:Blobs key:

JSON — appsettings.json

{
  "Aspire": {
    "Azure": {
      "Storage": {
        "Blobs": {
          "DisableHealthChecks": false,
          "DisableTracing": false,
          "ClientOptions": {
            "Diagnostics": {
              "ApplicationId": "myapp"
            }
          }
        }
      }
    }
  }
}

Inline delegates. Pass an Action<AzureStorageBlobsSettings> to configure settings inline:

C# — Program.cs

builder.AddAzureBlobServiceClient(
    "blobs",
    settings => settings.DisableHealthChecks = true);

You can also configure BlobClientOptions:

C# — Program.cs

builder.AddAzureBlobServiceClient(
    "blobs",
    configureClientBuilder: clientBuilder =>
        clientBuilder.ConfigureOptions(
            options => options.Diagnostics.ApplicationId = "myapp"));

Client integration health checks

Aspire client integrations enable health checks by default. The Azure Blob Storage client integration:

• Adds the health check when DisableHealthChecks is false, which attempts to connect to the Azure Blob Storage service.
• Integrates with the /health HTTP endpoint, where all registered health checks must pass before the app is considered ready to accept traffic.

Observability and telemetry

The Aspire Azure Blob Storage client integration automatically configures logging, tracing, and metrics through OpenTelemetry.

Logging categories:

• Azure.Core
• Azure.Identity

Tracing activities:

• Azure.Storage.Blobs.BlobContainerClient

Metrics are not emitted by default due to limitations with the Azure SDK.

Read environment variables in C#

If you prefer not to use the Aspire client integration, you can read the Aspire-injected blob endpoint from the environment and create a BlobServiceClient directly using the 📦 Azure.Storage.Blobs NuGet package:

C# — Program.cs

using Azure.Identity;
using Azure.Storage.Blobs;

var blobEndpoint = Environment.GetEnvironmentVariable("BLOBS_URI");

var client = new BlobServiceClient(
    new Uri(blobEndpoint!),
    new DefaultAzureCredential());

// Use client to interact with Azure Blob Storage...

Go

Install the Azure Storage Blobs SDK for Go:

Terminal

go get github.com/Azure/azure-sdk-for-go/sdk/storage/azblob
go get github.com/Azure/azure-sdk-for-go/sdk/azidentity

Read the injected environment variable and connect:

Go — main.go

package main

import (
    "os"
    "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
    "github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
)

func main() {
    // Read the Aspire-injected blob service endpoint
    blobEndpoint := os.Getenv("BLOBS_URI")

    cred, err := azidentity.NewDefaultAzureCredential(nil)
    if err != nil {
        panic(err)
    }

    client, err := azblob.NewClient(blobEndpoint, cred, nil)
    if err != nil {
        panic(err)
    }

    _ = client
    // Use client to interact with Azure Blob Storage...
}

When running against the Azurite emulator, use the ConnectionString environment variable instead:

Go — main.go (Azurite)

package main

import (
    "os"
    "github.com/Azure/azure-sdk-for-go/sdk/storage/azblob"
)

func main() {
    connStr := os.Getenv("BLOBS_CONNECTIONSTRING")

    client, err := azblob.NewClientFromConnectionString(connStr, nil)
    if err != nil {
        panic(err)
    }

    _ = client
}

Python

Install the Azure Storage Blobs SDK for Python:

Terminal

pip install azure-storage-blob azure-identity

Read the injected environment variable and connect:

Python — app.py

import os
from azure.identity import DefaultAzureCredential
from azure.storage.blob import BlobServiceClient

# Read the Aspire-injected blob service endpoint
blob_endpoint = os.getenv("BLOBS_URI")

credential = DefaultAzureCredential()
client = BlobServiceClient(account_url=blob_endpoint, credential=credential)

# Use client to interact with Azure Blob Storage...

When running against the Azurite emulator, use the ConnectionString environment variable instead:

Python — app.py (Azurite)

import os
from azure.storage.blob import BlobServiceClient

conn_str = os.getenv("BLOBS_CONNECTIONSTRING")
client = BlobServiceClient.from_connection_string(conn_str)

# Use client to interact with Azure Blob Storage...

TypeScript

Install the Azure Storage Blobs SDK for JavaScript:

Terminal

npm install @azure/storage-blob @azure/identity

Read the injected environment variables and connect:

TypeScript — index.ts

import { BlobServiceClient } from '@azure/storage-blob';
import { DefaultAzureCredential } from '@azure/identity';

// Read the Aspire-injected blob service endpoint
const blobEndpoint = process.env.BLOBS_URI!;

const credential = new DefaultAzureCredential();
const client = new BlobServiceClient(blobEndpoint, credential);

// Use client to interact with Azure Blob Storage...

When running against the Azurite emulator, use the ConnectionString environment variable instead:

TypeScript — index.ts (Azurite)

import { BlobServiceClient } from '@azure/storage-blob';

const connStr = process.env.BLOBS_CONNECTIONSTRING!;
const client = BlobServiceClient.fromConnectionString(connStr);

// Use client to interact with Azure Blob Storage...

提示

If your app expects specific environment variable names different from the Aspire defaults, you can pass individual connection properties from the AppHost using WithEnvironment. See Customize Azure resources for more information.